The invention concerns a wall exchange for telephone systems, particularly key systems, in which a baseplate is fixed to a support wall and in the lower portion of said baseplate are connecting strips with multiple contact strips pointing upwards. In addition, there is a component holder having on its backside a wiring card fitted with multiple plugs in its lower end, and in which the component holder is mounted with the wiring card multiple plugs inserted into the multiple contact strips in a slanted forward direction and by swinging the component holder toward the wall it is locked together with the baseplate.